366 PROCEEDINGS OF THE GEOLOGICAL SOCIETY, [ Mar. 9, 
So variable are the D beds here, that the excavation of a few 
yards will entirely alter the details of the section. Limestone will 
be replaced by sand, sand by ironstone, and either by limestone 
again, with every conceivable variation of change. A limestone 
band, however, about midway of the section, seems to be pretty con- 
stant—a circumstance frequently observable in other sections of this 
series, whether the beds above or below be calcareous or not. 
With regard to the underlying series, E, I have observed much 
variation in thickness according to locality, but that, where any 
considerable development of thickness occurs, a greater uniformity 
of character is exhibited than in the D beds. I would note also, 
although the presence of iron in such proportion as to constitute 
iron-ore is generally the prominent feature of the beds E, that it is 
not uniformly so. Over a considerable area north of Northampton, 
the calcareous predominates over the ferruginous character of these 
beds. On the other hand, in some few localities, certain of the beds 
of D contain iron in sufficient quantity, probably, to render them 
available for smelting-purposes. 
The following is the section of the pit at one point; and although 
it will not tally with the section at a few yards’ distance, it will serve 
to give a general idea of one phase of the D and E series of beds. 
Section of Mr. Bass’s Pit. 
{tines ategiae 
1. Very ferruginous sandstone, in thin layers .........ces..sesesseeeseereee Ae) 
2. Soft ferruginous sandstone, in two beds, sometimes extracted in large 
locks Meas. ce seeessa passer jenansec-e ese soeacaces ss esderceoniaascoreminecn sees 4 0 
3. Orange sand with rounded limestone masses .....-.sseseceseeceesseeeec 3 0 
4. Flaky hard ironstone with ochreous Cores .......e+se+ses-seeee I Oftoy 16 
5. Coarse sand with thin layers of sandstone, rounded at the edges, with 
numerous fragments of shells, joints of Pentacrinus, &. 1 Oto 2 O 
6. Caleareous flaggy bed, blue-hearted, sometimes crystalline and very 
hard, containing Rhynchonella cynocephala (?) and numerous F. 
vartabilis, and MUCH WOO ........0..sseeeceseeer-aee afew inchesto 1 6 
(ay Red arenacep us shOWe ies etasseae eee saaserereee ce -eacneree steer 3.0 
8. Ironstone in irregular beds, having a cellular texture with ochreous 
cores, varying in richness, and containing numerous shells in 
places | oe... De taee toed ne ROP eee asc ec a te GP OMorZa80 
9. Limestone bed, with green centres, sometimes hard, and containing 
BVO GOL ene eee eee eiee-e omens selse ne apes nee emer eee ieee eee leO 
10. An ironstone bed, with green argillaceous cores, full of rounded 
pebbles or concretionary nodules: this bed answers to the bottom 
bed of the Northampton Sand in the Kingsthorpe brick-pit 7. 
Tt contains Ammonites OifTONS ...0.0...csocsccscacencavencecssceossasss- 1 0 
In this section, the points of interest are—the zone, no. 6, which 
contains more than one species of Rhynchonella, including variabilis 
and, I believe, cynocephala, and the lowest bed, no. 10, in which, 
not unfrequently, is found Ammonites bifrons. Mr. Judd has col- 
lected from a calcareous bed, 3 feet thick, immediately overlying the 
Upper Lias at Brixworth (probably answering to bed no. 9 in this 
section), a decisive example of Rhynchonella cynocephala. 
The occurrence of these distinctive forms has induced me to in- 
clude this Rhynchonella bed (no. 6) and all below it in my division E 
